At Baselworld Zenith will introduce the second generation of the El Primero Lightweight, an ultra-light chronograph featuring a carbon fibre case and titanium movement, equipped with its signature 36,000 bph El Primero movement.

Zenith launched the first El Primero Lightweight late last year, claiming the title of the world’s lightest automatic chronograph. Freshly launched at Baselworld 2014, the second generation El Primero Lightweight is largely similar to the original in materials and weight, with a few key differences in function and aesthetics.

The key mechanical difference between the two Lightweight chronographs is the Striking 10th function found in last year’s model, which contained the El Primero cal. 4052 movement. The first generation had a central seconds hand travels once around the dial every ten seconds, enabling it to record elapsed times of up to 1/10th of a second.

The new Lightweight, on the other hand, is powered by the conventional El Primero cal. 400B, with a central seconds hand that takes one minute, or 60 seconds, to go around the dial. It is essentially a conventional, mechanical chronograph.

Aside from this key difference, the new Lightweight chronograph is largely the same. The 400B movement has its bridges and base plate in titanium, reducing its weight by a quarter. And its escape wheel and pallet fork are made of silicon.

It retains the same, 45 mm ceramic-coated aluminium and carbon fibre case, with a basic structure of aluminium covered by layers of carbon fibre. But the skeleton dial has blue accents, giving it a more muted look than the red and black Lightweight of last year.

With all the weight savings from materials and open-working, the Lightweight chronograph will weight about 40 g without strap, just like last year’s model.

Fitted with a Nomex-covered rubber strap, the El Primero Lightweight is limited to 250 pieces with a retail price of 17,500 Swiss francs, which is equivalent to about US$19,800. That’s a tenth less than the first Lightweight model, which was limited to 100 pieces.